The present invention relates to a printer for printing information onto a recording medium and, more particularly, to an improved top cover assembly mounted to a body of the printer.
A printer is known, which serves as, for example, a peripheral instrument of a computer. The known printer has defined therein a plurality of predetermined transport paths for a recording medium such as a continuous form, cut-sheets or the like. A suitable one of the predetermined transport paths is selected in compliance with the types of the recording medium and feed modes thereof such as a normal feed mode, inch-cut feed mode and the like. Specifically, in case where information is printed onto the continuous form, the continuous form is fed into and drawn out of the printer body through a rear opening formed in the printer body. On the other hand, when an automatic cut-sheet feeder installed on the printer body is utilized to feed the cut-sheets one by one into the printer body, or when the cut-sheets are fed manually one by one into the printer body, the cut-sheets are fed into and drawn out of the printer body through an upper opening formed in a top cover mounted on the printer body.
The printer provided with the plurality of openings for the recording medium, in particular, an impact-type dot-matrix printer has the following problem. That is, in the impact-type dot-matrix printer, a plurality of electromagnetically actuated wires of a printing head strike the recording medium during printing, so that vibration due to the striking is propagated along the surface of the recording medium and is magnified. By this reason, if the opening for the recording medium, which is not utilized, is kept open, considerable noises resulting from the printing operation leak to the outside through the opening kept open.
Accordingly, it is desirable that the opening, which is not utilized at the present time, in particular, the upper opening located in the vicinity of the printing head or a platen and faced to an operator, is closed during the printing operation. Moreover, it is preferable that the opening degree of the upper opening is kept as small as possible even during the use of the upper opening.
Conventionally, a top cover assembly, in which an acoustic insulation shutter is combined with the top cover, has been utilized to cope with the above-discussed problem. That is, the shutter is mounted to the top cover for sliding movement therealong and relative thereto between a closed position where the shutter closes the upper opening formed in the top cover and an open position where the shutter opens the upper opening.
FIGS. 11a through 11c of the accompanying drawings diagrammatically show the conventional top cover assembly 100 composed of the top cover 101 and the shutter 103 described above. As shown in FIG. 11a, the shutter 103 is mounted to the top cover 101 for sliding movement therealong and relative thereto in a direction indicated by an arrow, between the closed position shown in the figures where the shutter 103 closes the upper opening 102 formed in the top cover 101 and the open position where the shutter 103 opens the upper opening 102. FIG. 11a shows a feed mode in which information is printed onto the continuous form 105 while the latter is fed around a platen 104 in a direction indicated by an arrow and, subsequently, the continuous form 105 is drawn out of the printer body through the rear opening 106. On the other hand, in case of a feed mode in which a cut sheet is fed into the body through the upper opening 102, is passed around the platen 104 and is discharged out of the body through the upper opening 102, the shutter 103 is slidingly moved to the open position to open the upper opening 102.
The top cover assembly 100 is mounted to the printer body for pivotal movement relative thereto about a pair of pivots 107 (only one shown) between a closed position shown in FIG. 11a and an open position shown in FIG. 11b. The top cover assembly 100 is moved angularly to the open position for the purpose of, for example, replacement of a print ribbon, and after a new print ribbon is loaded, the top cover assembly 100 is returned to the closed position to resume printing. In this connection, when the top cover assembly 100 is moved angularly from the closed position shown in FIG. 11a to the open position shown in FIG. 11b, the leading edge portion of the continuous form 105 may frequently come out of a feed passage 108 defined between the top cover 101 and the shutter 103. If the top cover assembly 100 is returned to the closed position with the leading edge portion of the continuous form 105 maintained out of the feed passage 108 as shown in FIG. 11b, there is such an anxiety that the leading edge portion of the continuous form 105 fed around the platen 104 is jammed within the printer body and is damaged.